Probing Strangeness Production in Proton-Proton Collisions with Three-Particle Correlations

Abstract

Strangeness production in small systems such as proton-proton collisions is here investigated through the use of three-particle correlations in the momentum-space coordinates η and ϕ. This method is used in order to investigate possible correlation between conservation of both strangeness and baryon number, such that the particles chosen are Λ¯pK+ and the respective charge conjugates, where Λ is a strange baryon, p¯ balances: the Balance Function and the comparative restriction of relative positions for pairs of particles within given triplets. The development of normalisation, visualisation and triggering methods are tailored to the problem. The data used is produced by two implementations of the Lund String Model within the Monte Carlo event generator PYTHIA8. Such implementations are the default LSM as well as the string junctions method. The results show a tendency for balancing baryon number and strangeness to be localised nearby, most often close to the strange baryon as well, both in azimuthal angle and pseudorapidity. This signal is less localised within the junction model, which is believed to be more representative of the future phenomenological studies it is intended to compare this research to.

Popular Abstract

Particle Physics studies the physics at very small scales. Everything we know is composed of atoms. The atoms then are formed by electrons, neutrons and protons. Electrons are one of the particles that can not be split into smaller components, and therefore it is part of the group of fundamental particles. Neutrons and protons can be split into two types of quarks: up and down. These in turn can not be further split. In total, there exist 6 known quarks. All these elemental particles and their interactions are described by the Standard Model. The Standard Model is so far an extremely successful theory that describes the visible universe. It has been able to predict many of the known particles before they were discovered.

During the first 0.00001 seconds of our Universe’s life (to put this into scale, the Universe has existed for 13.7 billion years), the Universe was filled with a hot soup of quarks, anti-quarks and gluons. This hot soup is known as Quark Gluon Plasma or QGP. It is believed that with an understanding of QGP will come an understanding of nuclear matter in the deconfinment regime. This is a very fundamental question and our hopes are high. However, to be able to understand QGP, we would need to study it closely.
Is it even possible to do so? QGP seems to have been successfully produced in particle
accelerators. However, we are still a long way from understanding how it behaves.

Certain behaviours that we thought indicate the production of QGP and that should
only be possible when colliding two heavy nuclei, have also been observed when colliding
protons. This doesn’t necessarily imply that we were wrong. Rather, it means that we
need to take a step back and try to better understand the behaviour and interaction of
quarks.

There are heavier quarks than the up and the down. One of these quarks, the strange
quark, together with up and down, form particles that are often observed in collisions.
Building spatial correlations of where these particles are produced, and what influences
said production, will provide some much needed insight into the underlying physics.

A novel way to look at this question is to study such behaviour through the conservation
of two quantum numbers: strangeness and baryon number, where strangeness is -1 for
every strange quark and +1 for every anti-strange quark, and baryon number is +1 for
each particle composed of 3 quarks, and -1 for each particle composed of 3 anti-quarks.
This requires the correlation to be done among three particles, where the relative positions of two of them hopefully would result in a tendency for the third one to be localised at certain positions. This would mean that the production of these groups of particles isn’t arbitrary and therefore there are some underlying mechanisms to be further studied and understood.

• author: Petricean, Melinda
• supervisor: Alice Ohlson
• organization: Particle and nuclear physics; Department of Physics
• course: FYSK03 20231
• year: 2023
• type: M2 - Bachelor Degree
• subject: Physics and Astronomy
• language: English
• id: 9119895
• date added to LUP: 2023-06-07 10:17:32
• date last changed: 2023-06-07 10:17:32